The present invention relates to improved tobacco-containing smoking articles and a method of making the same. More particularly, the present invention relates to foamed, extruded, tobacoo-containing smoking articles and to an improved method of making such articles.
It is known to make non-foamed, extruded, tobacoo-containing smoking articles such as are disclosed in commonly assigned U.S. Pat. No. 4,391,285 which issued July 5, 1983. The tobacco-containing smoking articles disclosed in that application are articles wherein tar delivery during combustion is controlled by adjusting the density, porosity, surface area or composition of the article. The article comprises a coherent mass of combustible tobacco-containing material having at least one through passage extending from a first opening in the surface of the mass to a second opening, remote from the first. The coherent mass is of a density and porosity such as to substantially occlude gas flow through the mass, while also being of porosity sufficient to support combustion of the mass when ignited.
A method of making the smoking articles of U.S. Pat. No. 4,391,285 is disclosed in commonly assigned U.S. Pat. No. 4,347,855 which issued Sept. 7, 1982. According to this method, a combustible tobacco material is mixed with one or more other ingredients, including a liquid, to provide a tobacco mixture which is then shaped under pressure into a discrete coherent mass; at least one passage is provided through the mass, and then the mass is dried. The mixture composition is selected and the shaping pressure and drying are controlled to impart to the mass a density and porosity such as to substantially occlude gas flow therethrough, and a porosity sufficient to support combustion of the shaped mass when it is ignited.
Formation of the coherent mass is preferably effected by extrusion of the tobacco mixture, which, for this purpose, preferably contains comminuted tobacco of mesh size less than about 30 mesh, and in an amount sufficient to provide a solids content in the mixture of from about 55 to about 75 weight percent. The burn characteristics of the tobacco article produced according to this method are improved by further processing the dry and coherent mass by re-wetting and subsequently re-drying the mass.
Commonly assigned U.S. Pat. No. 4,333,484, which issued June 8, 1982, discloses a modified cellulosic smoking material and a method for its preparation. The material does not contain tobacco and affords reduced particulate matter and puff count while having the flavor and aromatic qualities of natural tobacco. The smoking material comprises cellulosic material having incorporated therein a metal salt selected from the group consisting of calcium salts, magnesium salts, iron salts, and aluminum salts of various organic or inorganic acids. The cellulosic material is preferably selected from the group consisting of carboxymethyl cellulose and its salts, cross-linked carboxymethyl cellulose and its salts, methyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, ethyl hydroxyethyl cellulose, ethyl cellulose, hydroxyethyl cellulose, and combinations thereof.
The method of making the smoking article comprises forming an aqueous slurry of the cellulosic material, preferably in the form of loose and slightly beaten cellulose fibers, adding from about 5 to 40 percent by weight, based on the cellulosic material, of the metal salt; adding a foaming or blowing agent to the resulting slurry under conditions which do not allow the foaming or blowing agent to foam the slurry; and casting or extruding the slurry and then drying the cast or extruded slurry under such conditions wherein the slurry is foamed during the casting or extruding step or during the drying step.
The organic acid is preferably selected from the group consisting of formic acid, acetic acid, propionic acid, butyric acid, valeric acid, methylvaleric acid, isovaleric acid, hexanoic acid, heptanoic acid, octanoic acid, benzoic acid, phenylacetic acid, citric acid, malic acid, tartaric acid, gluconic acid, and malonic acid and its lower alkyl derivatives, and combinations thereof. The inorganic acid is selected from the group consisting of hydrochloric acid, sulfuric acid, phosphoric acid, carbonic acid and combinations thereof.
The slurry may also include from about 3 to 40 percent by weight of an additive selected from the group consisting the pectins and their sodium, potassium, ammonium, calcium or magnesium salts, alginic acid and its sodium, potassium, ammonium, calcium or magnesium salts, and combinations thereof.
The foaming agent is preferably added to the slurry while the slurry is under sufficient pressure to prevent premature foaming of the slurry. The foaming agent is selected from the group consisting of air, steam, inert gases, volatile hydrocarbons, and combinations thereof. Preferably, the foaming agent is selected from a group consisting of ammonium carbonate, ammonium carbamate, azides, hydrazides, peroxides, azodiacarbonamide, and combinations thereof.
Among the objects of the present invention are the following:
to provide a foamed, extruded, tobacco-containing smoking article which exhibits superior combustion properties and taste, as compared to those smoking articles produced by the aforementioned methods having reduced binder content;
to provide an improved method of making such foamed, extruded, tobacco-containing smoking articles wherein the extrudate is stronger and dryer; and
to extrude a tobacco-containing smoking article having a moisture content at or less than 25% OV, particularly less than 22% OV.